SUMMARYThe relative amounts of chlorophyllb(Cb) and various chlorophylla(Ca) forms in nine plant species were determined by computer analysis of low‐temperature absorption spectra.The results show that (a) the amount of Cbis inversely related to the sum of the amounts of the bulk Cafrom both photosystems, (b) a direct correlation is likely to occur between the amounts of Cband the Cabands peaking around 685 nm and 640 nm, and (c) no correlation exists between the amounts of Cband the Ca662 and Ca695 forms.These data are interpreted to suggest that Cbis capable of taking over the antenna function of the bulk Ca, whereas it may occur in a complex carrying the Ca685 form as wel